Conventionally, in the manufacture of cellulose esters filaments, the filaments are not lubricated until after they leave the spinning cabinet. One reason for this practice is to avoid the contamination of the solvent used in the extrusion of the cellulose ester filaments with the lubricant.
Conventionally, in the manufacture of cellulose ester filaments, the cellulose ester polymer is dissolved into a solvent, that solution is known as dope. The dope is pumped to a die (or jet or spinneret) having a plurality of holes therethrough. The die is typically located at the upper end of a spinning cabinet. When the dope exits the die, the solvent flashes from the dope and the filaments begin to solidify. While the filaments travel downwardly through the cabinet, the solvent is captured within the cabinet for reuse. At the bottom of the cabinet, there is an outlet through which the filaments exit the cabinet. Typically, the filaments are guided from their downward (or vertical) travel to a generally horizontal direction (including angles below the horizontal) of travel at the outlet of the cabinet. The guide may be any conventional guide device, but it does not lubricate the filaments as their direction is changed. Thereafter, the filaments exit the cabinet. After exit, the filaments are lubricated by a lubricator, for example, a kiss roll. This lubricator is typically located about 6-12 inches (15-30 cm) from the exit of the cabinet. Then, the filaments are drawn away by a feed roll.
It is believed that the filaments are damaged as they pass over the non-lubricated guide. This damage causes variability in the filament.
There is a need to make a more uniform and more robust filament product.
Japanese Application No. 2003-020952 (Publication No. 2004-232124) discloses a method for manufacturing cellulose acetate tow where finish (oil) is metered on to filaments of the tow band at the point where the various thread lines from the cabinets are converged. The point of convergence is away from the cabinet exit.
U.S. Publication Nos. 2005/0202179 and 2005/0202993 disclose a finish for improving plug making that is applied, through existing fiber finish applicators, as the filaments exit the spinning cabinet. These publications do not mention the problem solved in the instant application.